The present invention generally relates to a steering wheel for reducing occupant injuries in a vehicle collision.
In order to provide additional protection against injury, vehicle manufacturers have designed several interior components for absorbing energy in a collision. These components include but are not limited to interior trim components, seating systems, instrument panels, windshields and steering wheels.
With respect to steering wheels, generally steering wheels are formed of plastic material having an internal member. Traditional steering wheels typically include an exterior cover which surrounds an inner metal member. The exterior cover is made of a somewhat stretchable, flexible, tough skinned and nonabrasive plastic material. However, upon impact with a vehicle occupant, the steering wheel of the prior art is capable of absorbing a limited amount of energy. In order to improve this feature, some prior art steering wheels have steering columns which are able to collapse on impact. Examples of such steering columns are disclosed in U.S. Pat. Nos. 5,820,163; 6,152,488; and 4,627,306. Such structures tend to be both complex and costly.
Another known structure for reducing injury is described in U.S. Pat. No. 3,331,260 issued to Zeller. The steering wheel of the ""260 patent is a steering wheel with rings having an exterior layer, a reinforcement ring made of metal, a hard rubber core and one or more superimposed veneer sheets vulcanized to the core. The steering wheel of the ""260 patent discloses the wooden veneer being integrally connected to the hard rubber core. The exterior wood layer of the steering wheel is further divided in segments whose veins are at right angles to the periphery of the wheel so that upon impact with a vehicle occupant the wood layers separate at the veins.
However, the steering wheel of the ""260 patent and other known plastic/metal steering wheels does not crush upon impact with the vehicle occupant. As noted, the steering wheel of the ""260 patent includes wood veneer sheets which are vulcanized to the hard rubber core. Accordingly, the wood veneer sheets of the ""260 patent absorb little energy upon impact.
Consequently, a need has developed for an inexpensive steering wheel which absorbs energy upon impact with a vehicle occupant in a collision.
The invention addresses the shortcomings of the prior art by providing a steering wheel having a plurality of layers which crushes and absorbs energy under pre-determined loads in a vehicle collision thereby reducing occupant injuries.
Under the invention, the energy absorbing steering wheel preferably includes an armature and an inner foam member surrounding the armature, a first plurality of exterior layers, and optionally a second plurality of exterior layers. The armature is mounted onto a steering column and is operative to provide a rigid steering wheel structure. The inner foam member surrounds the armature and has a first side and a second side. The first plurality of exterior layers is disposed on the inner foam member. Where there is a first plurality of exterior layers and a second plurality of exterior layers, the first plurality of exterior layers is disposed on the first side of the inner foam member and the second plurality of exterior layers is disposed on the second side of the inner foam member. The second plurality of exterior layers and the first plurality of exterior layers may slide with respect to each other when impacted by a vehicle occupant in a collision.
Generally, at least one layer in the first plurality of exterior layers and at least one layer in the second plurality of exterior layers define channels or apertures to allow the layers to crush upon impact with a vehicle occupant. The channels or apertures may have varying cross-sections to allow for greater crush in pre-determined areas of the steering wheel.
The steering wheel layers may, but not necessarily, be made of wood, plastic, fiberglass, or any combination of these materials.
As those skilled in the art will recognize, the embodiments of this invention may vary depending upon the specific requirements of a vehicle. Accordingly, the particular size and shape of the armature, the inner foam member, the first plurality of layers, and the second plurality of layers may vary, depending on the particular application.
These and other objects, features and advantages of the invention are readily apparent from the following detailed description of the best modes for carrying out the invention, when taken in conjunction with the accompanying drawings.